Applied Sciences special issue on “Design and System Integration of Thermal Energy Storage”

The worldwide commitment towards cleaner development by scaling down hazardous carbon emissions to avoid dangerous climate change calls for solutions that allow for the exploitation of renewable energy sources, and waste heat streams, reducing the energy consumption of systems in residential and industrial sectors. On the other hand, increasing human thermal comfort in micro and macro environments is of critical importance and requires innovative and advanced technologies.

One of the enabling technologies in this view is thermal energy storage (TES), which represents an essential component in a system architecture devoted to the maximisation of the share of renewables and energy efficiency. The intense research devoted to TES has led to the commercialization of different solutions, as well as the advancement of several TES systems for the most various applications from lab-scale towards full-scale real applications.

Our HYBUILD partner CNR ITAEValeria Palomba – is acting as Guest Editor, together with Dr. Mohammad Saffari from University College Dublin, for a Special Issue of MDPI journal Applied Sciences on the topic of “Design and System Integration of Thermal Energy Storage“.

Deadline for contributions is 31 October 2020 and further details are available through this link.

Energy Technologies and Restoration of Vernacular Architecture

A one-day symposium was organised by Aglantzia municipality and the University of Cyprus, with the aim to benchmark the progress of the HYBUILD project, to highlight the environmental aspect of vernacular architecture and to demonstrate ways of restoration using energy technologies.

30 persons attended the event, both professionals (designers, ICT installers, energy advisors), municipal councils representatives, construction and engineering companies, academia, Scientific community, and general public.

Professionals demonstrated their interest for the project and discussed extensively the value of restoration of vernacular architecture, and the need to introduce new policy to favour acceptance of such systems in such buildings typology. The HYBUILD concept is one step further in this direction.

With its pilot site in Aglantzia, HYBUILD contributes the rejuvenation of the area, as it will become a reference point in the historical core of Aglantzia through investment in research. The retrofit of the building as a multifunctional center and as an exhibition show-room for renewable energy technologies will have a positive impact on society.

Learn more about the Cyprus pilot site here.

Introducing Almatret, HYBUILD pilot site

HYBUILD is a group of 21 partners from 9 countries. Every month, a new HYBUILD partner is introduced in our Blog section. This month, we present the Town of Almatret which will host one of the HYBUILD pilots.

Almatret in a nutshell

Almatret is a rural village in Catalonia, Spain, next to the Ebro River, about two hours inland west of Barcelona. It is ringed by agricultural fields of mainly olive and almond trees, as well as protected natural landscapes in the surrounding hills.  Many visitors come to Almatret for trekking, mountain biking and fishing in the river, among other outdoor activities.

The village has a rich history in the production of energy.  In the 19th and 20th centuries, coal mining was the main local employer. In the 1960s, the Ebro River was dammed 6km downstream for the creation of hydroelectricity.  In the 1970s, a nuclear power plant was built 17km from Almatret. Since 2009, the village now has 44 Wind Turbines, with a combined capacity of over 106MW, as well as solar farms and solar panel installations.

Like most rural villages in the Spanish interior, Almatret is suffering from severe depopulation.  From its peak census of 1,520 in 1920, there are now only 204 residents who live year-round.  Over 50% of these residents are over 65 years old.  The local school was finally closed in 2012.

In an effort to combat the effects of depopulation and promote tourism, Almatret created a project in 2016 called ALMIA (“ALMatret + energIA”), in partnership with the GREiA Research Group at the University of Lleida.  The goal is to convert the village into a destination for ecotourism, educational visits and R&D projects.  The closed school building and grounds have been converted into an R&D center, currently for the H2020 Innova and HyBuild projects.  The building is being remodeled to include an educational museum for renewable energies, meeting spaces for tours, labs for research groups, as well as a hostel for visitors who wish to stay overnight.

Almatret’s role in HyBuild

The old school building and grounds will house the Mediterranean installation of the HyBuild project, and will connect to the adjacent “Doctor’s House”, which is the village doctor’s residence. In addition to refurbishing and maintaining the buildings and grounds for the demo, Almatret will assist University of Lleida in any day-to-day needs and facilitate and coordinate all visits to the site by HYBUILD partners.

Follow the HYBUILD Almatret pilot site roll-out on this page.

Get in touch !

Richard Lyon is the European Project Manager for the Municipality of Almatret.  He holds a bachelor´s degree in International Business Administration and Marketing from The University of Oklahoma (USA).  He has worked for over 10 years as an international project manager and business development professional in the software, technology and telecommunications industries. Some of his interests include: ecotourism, rural development and repopulation, sustainable energy and educational programs for renewable energy. He lives with his wife and two daughters in Almatret.

Researcher’s night 2019 in Athens

HYBUILD project was presented during the NTUA (National Technical University of Athens) participation in the annually organized pan-European science and research fair “Researchers’ Night 2019”.

During this evening, several scientific research projects were presented to the wider public. The event was attended by members of the academic community from all over the world, while also including school visits.

NTUA booth at the Athens Researcher Night 2019

The event was advertised in the media, attracting a large number of citizens, mainly families with young children, eager to become familiar with the latest achievements in European technology and research.

Learn more about the event at

HYBUILD at the European Researchers’ Night 2019

European Researchers’ Night 2019

European Researchers’ Nights are public events dedicated to bringing researchers closer to the public. They showcase the diversity of research and highlight the impact of research on our daily lives. The aim is also to motivate young people to embark on research careers. The events promote how researchers contribute to our society by displaying their work in an interactive and engaging forum.

Once again this year, HYBUILD was present at the 2019 Researchers’ Night at the University of Lleida which welcomed more than 400 visitors.

A roll-up describing the HYBUILD project was placed at the Europe’s Corner of the event dedicated to the EU projects in which UDL is involved.

European corner at UDL Researcher Night 2019

Participants had the opportunity to get in touch with European research and know more about the new technologies and the current challenges that the actual research is dealing with in different areas. HYBUILD approach to tackle these challenges was explained to those participants who showed interest on the topic.  

Luisa F. Cabeza & Gabriel Zsembinszki at UDL Researcher’s night 2019

Further info at (Spanish) :

HYBUILD at Innovative City in Nice

Regis Decorme from R2M Solution attended and disseminated HYBUILD at Innovative City 2019 | Innovation for Better life and Smart Business | in Nice, France, 15 October 2019.

This new edition of Innovative City had a specific track focused on Smart Grids, which highlighted local demonstration projects such as FLEXGRID, as well as other local initiatives being led by the Smart Grids cluster of the French Riviera Chamber of Commerce.

HYBUILD energy storage solutions can play a significant role in terms of flexibility for the next-generation energy networks.

Read further about Innovative City at

Integration of a compact two fluid PCM heat exchanger into the hot superheated section of an air source heat pump cycle for optimized DHW generation

A new HYBUILD conference paper was presented at the 25th IIR International Congress of Refrigeration, Montreal, Canada, August 24−30, 2019.

This contribution presents a concept for the direct integration of a refrigerant/water Heat Exchanger (HEX) with a Phase Change Material (PCM) in the hot superheated section of an R32 – air source compression Heat Pump (HP) cycle, for optimized Domestic Hot Water (DHW) generation in multi- family houses. The concept takes advantage of the PCMs high thermal storage capacity integrated into a high performance compact enhanced plate-and-fin aluminium HEX. On the refrigerant side, it works as a de-superheater for DHW generation during heating and cooling operation whereas the process water is connected to decentralized DHW storages located in single apartments of a low energy building. We present results from simulations at a system level for typical operating conditions and corresponding seasonal and annual performances. Compared to conventional systems, the results indicate savings up to 11% of electric energy over the year for DHW generation in average climate.

Read the full paper on the Scientific publications page.

Copyright © IIF/IIR. This paper is published with the authorization of the International Institute of Refrigeration (IIR):

Phenomenological modelling of phase transitions with hysteresis in solid/liquid PCM

A new HYBUILD paper has been released in the Journal of Building Performance Simulation.

Technical-grade and mixed solid/liquid phase change materials (PCM) typically melt and solidify over a temperature range, sometimes exhibiting thermal hysteresis. Three phenomenological phase transition models are presented which are directly parametrized using data from complete melting and solidification experiments. They predict hysteresis phenomena and are used to calculate effective PCM properties. Two models have already been implemented in commercial building simulation and/or multiphysics software, but not the third novel model. Applications are presented for two commercial PCM: a paraffin, and a salt water mixture with additives. Numerical implementation aspects are discussed, and significant differences in the predicted absorbed and released heat are highlighted when simulating consecutive incomplete phase transitions. The models are linked with energy balance equations to predict recorded PCM temper- atures of a thermal energy storage. The cross-validation with data from 26 partial load conditions clearly indicate a superior predictive performance of the novel hysteresis model.

Link to the full paper

FRESNEX collectors installed at the HYBUILD Spanish demo site

At the HYBUILD Spanish demo site located in Almatret, solar collectors provided by FRESNEX have just been successfully installed. Local stakeholders, in particular from the town of Almatret and from University of Lleida, have been trained on the overall system functioning and on its control / tracking system.

Fresnex solar collectors in Almatret, HYBUILD Spanish demo site 

Fresnex solar collectors in Almatret, HYBUILD Spanish demo site

During the upcoming months, this system will be incrementally integrated with the other technological components, to form the overall HYBUILD hybrid storage solution.

Further information about Almatret & the Almia initiative : 

Introducing HYBUILD’s heat exchanger manufacturer: AKG group

HYBUILD is a group of 21 partners from 9 countries. Every month, a new HYBUILD partner is introduced in our Blog section. Today: AKG – the cooling experts, manufacturer of the heat exchangers for the project.

AKG in a nutshell

The AKG group of companies – A strong global group of companies

As a leading supplier of customer-oriented solutions, AKG has acquired an internationally acclaimed reputation for producing reliable, high-quality radiators and heat exchangers.

The AKG Verwaltungsgesellschaft (holding company) in Hofgeismar, Germany directs the operation of the AKG Group, whose 2,800 employees produce over 2.5 million heat exchangers in various designs each year. To achieve this, 12 business units in Germany, France, Latvia, Turkey, India, USA, Brazil and China as well as 10 oversea sales companies are in operation twenty-four hours per day.

AKG develops and manufactures high-performance heat exchangers and complete cooling modules for application in construction equipment, compressed air equipment, industrial coolers, agricultural and forestry equipment, railroad vehicles, aviation, household appliances and special applications.

For 100 years AKG Heat-Exchangers are standing for innovative solutions as well as highest engineering and manufacturing competence.

AKG’s role in HYBUILD

AKG builds the aluminium heat exchangers for the HYBUILD-project.

AKG offers a wide range of heat exchanger designs, which includes brazed bar-plate coolers, stacked-shell coolers as well as various types of tube-and-fin heat exchangers.

For compressed air application AKG is not only providing the coolers for oil or compressed air but also evaporators for refrigeration dryers. For one customer AKG already manufactures evaporators with integrated thermal storage (PCM) to improve the performance of the refrigeration system. The similar design principle is used to store thermal energy for the hot and cold storage for the HYBUILD-project. Integrating the PCM directly in the heat exchangers allows a compact and fast reacting storage solution.

Beyond customized solutions for various industries AKG also manufactures special heat exchangers for research institutes to help promote new technologies.

Following are photos of some of the special heat exchangers that AKG has manufactured for use in the HYBUILD-project.

Picture of a lab-scale RPW-HEX (Refrigerant-PCM-Water-Heat Exchanger)

Picture of a full-scale RPW-HEX for installation in one of the demo-sites

Picture of a heat exchanger to act as adsorber after zeolite treatment

Get in touch: key staff from AKG involved HYBUILD

Dr. Katerina Hatesuer is project manager in the Research and Development department of the AKG group. She obtained her Bc. degree in mechanical engineering at the Czech Technical University in Prague (CZ) and her M.Sc. and later the Dr.-Ing. degree at the University in Kassel (D) first in engineering of Regenerative Energy and Energy efficiency (M.Sc.) and followed in Thermal Energy Management (Dr.). She has been joining AKG since August 2018 and is responsible for the thermal dimensioning of the heat exchangers.

Birgo Nitsch is project manager in the Research and Development department of the AKG group. He obtained diploma in Mechanical Engineering at the Technical University of Dresden. Since 1999 he has been working for AKG in the development of heat exchangers, with a focus on brazed and bonded heat exchangers for various applications (e.g. fuel cells, tumble dryers, heat pumps). He is also responsible for prototype building and the vacuum brazing shop.

Dr. Andreas Strehlow is director of Research and Development of the AKG group. He obtained a degree in chemical engineering and specialized in fluid dynamics at the Technical University of Dortmund. He works in the development of heat exchangers since 1994, where the focus was on large regenerative heat exchangers for power stations. He joined AKG in 2003 and is responsible for developing, building and testing of high performance heat exchangers for the AKG group.